/Engine/Source/Runtime/MeshConversion/Public/DynamicMeshToMeshDescription.h
Checks if element counts match. If false then Update can't be called  you must call Convert Result is based on the current ConversionOptions (e.g. if you are only updating vertices, mismatched triangles are ok)
bool HaveMatchingElementCounts ( const [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) * DynamicMesh, const [FMeshDescription](API\Runtime\MeshDescription\FMeshDescription) * MeshDescription )